The present invention relates to particular serotypes of Staphylococcus epidermidis, to a method of identifying these serotypes, and to a vaccine produced using these surface antigens associated with these serotypes. The invention also relates to methods of active and passive immunization of humans and animals infected with or susceptible to infection with Staphylococcus epidermidis.
Coagulase-negative Staphylococcus infections are a leading cause of bacteremia in hospitalized patients. In particular, S. epidermidis, formally thought not to be a pathogen, has been discovered to be a significant factor in this bacteremia. Morbidity and mortality from S. epidermidis infection is especially high among patients requiring prosthetic medical devices. This is thought to be a result of slime produced by S. epidermidis which permits adherence to and colonization of these medical examples, e.g., catheters and heart valves.
Because the slime is thought to be the factor responsible for infection by S. epidermidis, attention has focused on those aspects of the surface which mediate attachment to foreign bodies. An extracellular slime has been identified by various researchers, and culture conditions promoting production of this slime have been used.
In addition to a focus on the slime produced by S. epidermidis, research to date has largely been directed toward a limited number of specific strains of the bacteria which have been isolated. Ichiman et al. studied three strains of S. epidermidis, which they cultured in Brain Heart Infusion (BHI) broth. Immunization of mice with cell surface polysaccharides from these cultured microorganisms were not effective, however, in providing protection to heterologous strains. Characterization of the surface polysaccharides which were isolated showed serological heterogeneity. Ichiman et al., J. Appl. Bact. 51: 229-241 (1981).
According to Ichiman, in order to be an effective vaccine for clinical use, each infective strain would have to isolated and a vaccine developed against each strain. This would be untenable from a practical standpoint.